Microstructures such as microelectromechanical systems (e.g. micromirror devices, micromirror array devices, liquid crystal displays, and liquid crystal on silicon displays) are often fabricated on one or more substrates. For protection purposes, the microstructures are often packaged. A typical packaging often includes attachment of electrical connections (e.g. wire-bonding), environmental control (e.g. by hermetically sealing in an inert environment), physical protection of the microstructure (e.g. by encasing the microstructure in hard, strong materials), and alignment of the microstructure (e.g. to fixed alignment marks on the package). Part of this process is the bonding of the substrate of the microstructure to the package substrate with a die-attach adhesive. Due to built in stresses in the die, the adhesive, and the package, or due to thermally generated stresses (i.e. those arising from CTE mismatches of the components coupled with a temperature change), forces can be applied to the microstructure. In general such forces will cause deformation of the microstructure, which in turn leads to degradation in performance, even device failure of the microstructure especially when the deformation exceeds a tolerable amount.
Moreover, in those microstructures having multiple substrates, a uniform gap between two substrates is often required for ensuring desired functions or performance of the microstructure. The gap uniformity can not be guaranteed in the presence of such deformation.
Therefore, a method and apparatus for manufacturing microstructures that reduce the quality and performance degradation due to deformation are desired.